Generally, a vehicle is equipped with a battery for supplying electric energy to various kinds of electric component parts. Among such components, there are some high-voltage parts. For example, a hybrid vehicle that runs on combination of an electric motor and an internal combustion engine or an electric vehicle that runs only on the electric motor is equipped with not only the high-voltage parts that operate with a high-voltage direct current power from a high-voltage direct current power supply but also the high-voltage parts that operate by converting, as the electric motor does, the power supply voltage from the high-voltage direct current power supply into alternating current. Since a fuel cell powered vehicle also converts various types of fuel into electricity for running, it is equipped with the high-voltage direct current power supply.
In the vehicle equipped with this type of high-voltage direct current power supply, sufficient electrical insulation is provided so that the high-voltage direct current should not be flown into the power supply or any other high-voltage parts. However, the electrical insulating part may degrade for some reason to cause electric leakage. For this reason, there is a proposal for equipping an apparatus for detecting the electrical insulation degradation in a vehicle (an example is Patent Document 1).
There is another proposal for controlling the running function of the vehicle equipped with a high-voltage power supply to be maintained until the next running operation instruction is given (that is, the ignition key is switched on), instead of restricting its running immediately after the electrical insulation degradation is detected at a high-voltage part (an example is Patent Document 2).